Dental instrument for forming cervical margins



Jan. 14, 1930. F. s. MEYER 1,743,154

DENTAL INSTRUMENT FOR FORMING CERVICAL MARGINS Filed March 1928 3419- 29- //'a /0 //a/ W //b "a //b //& I

Patented Jan. 14-, 193% UNETE.

oFFICE DENTAL INSTRUMENT FOR FORMING CERVICAL MARGINS Application filed. March 5,

" and pull away from the margins. The excess wax is trimmed from all margins and the wax model is then removed. Usually where the above method is carried out sufficient pressure and heat arenot applied adjacent the gingival margins of the tooth to obtain a correct impression and as a result the casting made from the wax model does not perfectly fit the gingival margins.

It is an object of my invention to provide a simple instrument and a method for perfecting the gingival margins of wax models which will obviate the objections above noted and will cause the gingival margins of the wax model to be properly formed adequate heat and pressure being placed upon the wax at points adjacent said margins. I

A further object of the invention is toprovide a dental instrument so constructed as to be passed between the wax and the tooth adjoining the cavity, or more exactly between the adj oining tooth and a matrix surrounding the wax, which instrument is thin enough to penetrate interproximal spaces and still bulky enough to carry considerable heat and shaped properly to be easily inserted in the manner above described and to draw the gingival edge of the matrix against the adjacent portion of the tooth to be filled.

These and other objects and advantages of the invention will be apparent from the following description made in connection with the accompanying drawings wherein like reference characters refer to similar parts throughout the several views and in which Figs. 1 and 2 are side elevations of left and 1928. Serial No. 259,041.

right instruments for forming gingival mar- Figs. 3 and t are plan views of the upper ends of the instruments shown in Figs. 1 and 2;

Fig. 5 is an enlarged side elevation of the tip portion of the instrument shown in Fig. 1

Fig. 6 is a vertical section taken on the line 66 of Fig. 5;

Fig. 7 is a view showing the manner in which my instrument isutilized;

Fig. 8 is a view showing the manner in which the instrument is applied and passed between the matrix and the interproximal tooth; and

Fig. 9 is a plan viewof the usual matrix used in forming wax models.

As shown in the drawings, two instruments are provided which may be designated as rights and lefts, each comprising an elon-' gated shaft or handle 10 which is usually straight having a diminished working end 10 provided with a skewed laterally projecting blade 11. Blade 11 is of wedge-shaped cross section conforming in shape to the interproximal spaces between the teeth as shown in Fig. 6 and is slightly curved, tapering from the working end 10? of the handle to a sharp point 11 at the outer extremity thereof. The blade is so formed that the thinner concave edge 11 thereof is adapted to extend towards the occlusal surface of the tooth when applied, while the thickened concave edge is disposed adjacent the gum, the blade being curved to permit the instrument to reach beyond the gingival margin of the cavity with the least mutilation of the gum tissue on the buccal and lingual. The sides of blades 11 taper gradually from the place of connection of the blade with the handle to the point 11*. All edges of the blade are rounded to I prevent the blade from cutting and mutilating the gum tissue or scraping the teeth. The skew in the blade is formed by turning the blade on its longitudinal axis through an acute angle with the thickened convex edge disposed outwardly in order that when the shank or handle is held at an acute angle with the occusal surface of the teeth and the blade is disposed in an interproxirnal space,

the major portions or surfaces of the blade will touch the surfaces of the approximating teeth, or, as will hereinafter be set forth, the surface of a matrix applied to the approxi- V 5 mating teeth.

As shown in Fig. 8, one of my instruments is applied between interproximal teeth of a lower jaw, a thin matrix of the type illustrated in Fig. 9 is used in connection with 10 my instrument and has an important function in my method for perfecting gingival margins for wax impressions. Matrix M is first inserted between intcrproximal'teeth. My instrument is then appliedas shown in Fig. 8 handle 10 of aright instrument being disposedin inclined position and thebladell is passed inwardly between the matrix and'the acent side of the interproximal tooth 'to. the tooth to be filled. V Previousto the application of'the matrix and instrument Warm impression material :is lirst iforced in. the cavity and between the,

interproximal spaces or the tooth to be filled. Then as shown in Fig. '7 thegingival edge of .thematrixM is, positioned slightly below the gingival margin of the tooth. .My instrumentis then applied .haVi11gfirst been heated and pressureis placed against the matrix at the gingivalmargin or slightly below,the ma- ..30 trix being drawn inwardly against the tooth.

The wax isthus efficiently forcedagainst the gingival margins and slightly toward the root of thetooth, p ronucing a true impres Hsion. This'pr-ocess is followed forthe oppo- '35 site side of thevtooth .and .is repeated at the .distolingual, :mesiobuccal and ,mesiolingual angles.

.The blade 11 of the instrument is thin enough to. penetrateinterproximalspacesand 40 .still' bulky enough'to carry. considerable heat.

The blade iscurvedso that its thickened con- Y8X:.8Cl-g8 i will touch the gin givalrmargin the :cavity without laceratingithe, gingival on .the 'buckle-amd lingual. lVhen lateral pres sure is applied on the blade,.due to its struc 'ture, their-major portion 0 theopposing-sur- :face of the.bladewillcontact with thesurfaee of the matrix. The wax is thus softened and forced over the ,gingival marginsleaving the 5 matrixinthepositionshown atb in Fig. 7, zlwithaverysmall amount of excess wax at the -.gin-giv;al 'margins which can be easily tri mmed away.- The wax pattern is 1 completed with whatever technique is desired it 3b'eing advisable tohold the wax pattern .fsteaoly 1 while trinnning to avoid raising the same from the: gin gival margin. f

=F'ro-mithe;foregoing description it will be :seenrthat 'bytheuse of my improved instrufluent in the manner above described, Wax

'morlelslforrinterproximal inlays may be obtained-having substantially perfect gingival 'margins. The application of heat and pressure to the'matrix adjacent the gingival marginsforces the Wax inwardly as well as in the direction of the gums and causes a correct impression of the margins to be made. My instrument is especially shaped for insertion in the manner described, the cross section being of wedge shape and the blade portion being curved to permit the matrix to be drawn inwardly.

It will, of course, be understood: that Various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of the invention.

VJ hat is claimed is:

1. The method of perfecting the margins of wax impressions for interproximal inlays which consists in forcing warm-impression material between interproximal teeth, inserting a thin strip of conductive material .between the interproximal teeth and against said impression material andzapplyingsimul- .taneousl heat andnressure a ainst the ed e l D b of said stripadjacent the root of the tooth. 2. The method of perfecting the margins of wax impressions for interproximal. inlays which consists in forcing softened impression mate-rial in the interproximal spaces .of a

tooth to be filled, insertingv a thinstrip of conductive material between said impressionmaterial and a tooth adjacent said firstimentioned tooth, said strip extending to the root side of the gingival margins of the tooth to beifilled and applying simultaneously .heat and pressure. against said strip ofmaterial in the direction of the tooth to be filled, the point of application being adjacent the gingival margins of said last mentioned tooth.

3. A dental instrument for perfecting the margins of waximpressions for interproximal inlays, comprising an elongated shank, a portion of which constitutes a handle,.-a blade projecting laterally from one end-of said shank and tapering gradually from its place of connection with said shank to a well'defined point,said blade being substantially triangular in cross-section to conform as nearly as possible to the shape of the interproximal :spaces of the teeth and being curved with its thickened edge disposed outwardly to :prevent laceration of the gums,:said blade being alsoturned with respect to said shank on its longitudinal axis through anacute. angle in order that when the shank is held atsa-n'aoute angle with the occusal surface of the teeth the ln testimonywhereof'I affix my signature.

FREDERICK S. MEYER.

blade will fit .aninterproximalspace ofthe iteeth, the-edges of-sa-id blade being rounded ;to prevent cutting of thegu-ms or tissue. 

